With continuous advancement in science and technology, people are imposing ever higher requirements on communications. Nowadays, more and more importance is being attached to convenience of communications in addition to requirements on quality of communications. Among various communication means, wireless communications are advantageous in that they provide higher mobility by obviating the need of physical communication network wiring. Therefore, mobile products (i.e., mobile stations (MSs)) with wireless communication functionality such as cell phones, notebook computers and the like are getting more and more popularity in recent years and have become the mainstream products in the consumer electronics market.
However, in practical use, MSs operating in different locations have to be handed over among individual base stations (BSs) frequently in order to ensure a certain level of wireless communication quality. Taking a WiMAX network as an example, it features an ability to support mobile data access and, accordingly, defines two handover modes, namely, the fully controlled handover and the uncontrolled handover. Hereinbelow, operating principles of the two handover modes will be described in brief.
The fully controlled handover is characterized in that, prior to a handover process, an MS transmits, in advance, a handover request to a serving BS that currently provides network services and then, also in advance, the serving BS transmits data related to the MS to a target BS. The target BS also establishes a connection path in advance for use by the MS to transmit data after being handed over to the target BS. Upon completion of these operations, the serving BS informs the MS that the handover process may commence now. Then, the MS may be handed over to the target BS immediately and continue to use the services it previously used prior to the handover.
On the other hand, the uncontrolled handover mode is characterized in that, instead of transmitting a handover request to the serving BS in advance, the MS transmits the handover request directly to the target BS. In this case, the target BS must acquire data related to the MS from the serving BS and establish a connection for the MS before the MS can use services of the target BS.
As can found through comparison between the two handover modes, the fully controlled handover leads to less handover latency because information necessary for the handover is transmitted and a connection for use by the MS is established both in advance. Unfortunately, in practical applications, signals in the WiMAX network are often unstable due to various interference factors. Under such conditions, the handover process is more frequently accomplished in the uncontrolled handover mode instead of the fully controlled handover mode. This leads to considerable network latency in the handover process.
Accordingly, an need still exists in the art to provide a solution that can effectively reduce burden of the network associated with handover-related control information during an uncontrolled handover process, so as to improve the handover efficiency and performance of the network as a whole.